The present invention relates to an attenuator for single-mode optical fibers.
There is described, in EP-A No. 0063085, a connector for optical fibers that comprises two ferrules attached to the end of each of the fibers to be connected, and a female access coupler pierced lengthwise to support and align the two ferrules face to face. In the central part of the female coupler, inside its lengthwise pierced hole, is a thrust bearing body, particularly a sphere, for the male ferrules. The thrust bearing body has a transverse axial orifice and, around this, a contact projection opposite each of the male ferrules.
Each male ferrule has an axial tubular protuberance that can be inserted into the orifice of the thrust bearing body and a conduit into which the optical fiber can be introduced loosely and immobilized in such a way that its end coincides with the end of the protuberance. Each of the ferrules, moreover, has an annular groove set back from the protuberance and surrounding the back part of the latter. The wall of the groove, preferably conical in profile, defines a projection of contact with the projection opposite the thrust bearing body of the female coupler under the action of a longitudinal means of pressure. The projections opposite the body of the thrust bearing of the male ferrules are arranged in such a way that during any relative movement of the projections in contact with the end of a fiber at the level of the end of the protuberance of a male ferrule will remain at a predetermined, constant distance from the center of the thrust bearing body.
In order to obtain a certain attenuating function, the distance between the fiber ends in the male ferrules can be increased, for example, by increasing the diameter of the sphere that constitutes the thrust bearing body.
The connector described in the aforementioned European patent can thus constitute an attenuator for multimode optical fibers. It cannot, however, serve as an attentuator for single-mode optical fibers, because the distance between the fiber ends would be too great and would affect the characteristics of the transmitted field.